Dash pot carburetor control



1955 B. WALKER 3,216,62

DASH POT CARBURETOR CONTROL Filed March 28, 1962 United States Patent 3,216,692 DASH PUT CARBURETOR CONTRGL Brooks Walker, 1280 Columbus Ave., San Francisco 11, Calif. Filed Mar. 28, 1962, Ser. No. 183,185 8 Claims. (Cl. 25154) This invention relates to improvements in dash pots for control of the opening and closing ratio of a carburetor throttle. This is useful when applied to a motor vehicle for smog reduction in connection with a device, as shown in the F. V. Hall Patent No. 2,809,623 or with a smog reduction carburetor and linkage to operate said carburetor, as shown in US. application Serial No. 159,091, for Vehicle Throttle Control, filed Dec. 13, 1961, by applicant.

A feature of this invention is that the dash pot provides a graduated opening of the throttle on tramp down of the foot throttle so that the throttle opens at a slower rate as it starts to open than the rate of opening after the start so that the rate of change of the partial vacuum in the intake manifold will be gradual from idle partial vacuum of around 21" to full throttle manifold vacuum of under 2" hg. The total delay in throttle opening on tramp down being in the neighborhood of 2 seconds. The dash pot also controls the rate of closing with the greatest delay being in the final closing motion of the butterfly. The orifices are larger for controlling the rate of closing and the delaying force provided in closing by the dash pot is less in closing than in opening of the throttle.

Other dash pots have used two diameter cylinders or exterior parts and controls to get differing rates of resistance at differing parts of the dash pot stroke. This invention obtains the differing rates by a rod passing through the piston with flats of varying depths to form a variable orifice for variable resistance at different parts of the stroke.

Another object is to provide a throttle control that will give a reduced rate of opening even with high soft link pressure as the throttle starts to open after a sudden tramp down of the throttle pedal when held open compared to the later rate of opening of said throttle and also provide mechanisms so that said throttle can be closed much faster than the opening rate at each corresponding degree of open angle.

A slapper or check valve in a pasasge through the piston allows a different resistance in one direction of travel than in the other. The variable flats on the metering rod offer a change in the resistance during the stroke of the dash pot during the full stroke in either direction.

Another feature is the greater simplicity of construction of the dash pot and variable orifice than in previously known designs.

Other objects will be more particularly pointed out in the accompanying specifications and claims.

I have shown my invention by way of example in the accompanying drawings in which:

FIG. 1 is a side elevation partly cut away showing one form of the invention.

FIG. 2 is an enlarged top elevation of the center of the cylinder of the construction shown in FIG. 1 with the piston and rod partly cut away.

FIG. 3 is an end view partly in section and enlarged taken at Section 3-3 of FIG. 1.

FIG. 4 is a side elevation view in reduced scale showing the operation of a foot throttle in one form of the invention similar to that shown in FIGS. 1, 2 and 3.

In all figures like numerals of reference refer to similar parts.

In FIGS. 1, 2 and 3, I have shown a carburetor 9 3,216,692 Patented Nov. 9, 1965 with a float bowl 911, a butterfly throttle valve 7, a throttle shaft 8, a throttle lever 6. A throttle control rod 22 is connected to a throttle pedal in a conventional manner not shown. Collar 23- is secured to throttle rod 22 by pin 24. Collar 25 is secured to rod 22 by pin 26 near the end of rod 22. Collar 20 is slidably mounted on rod 22 and has pin 21 secured thereto. Pin 21 pivotally mounts on the upper end of throttle lever 6 and is pivotally secured to the hole near the right end of tie rod 19, as viewed in FIG. 1. Pin 17 joins the upper end of dash pot arm 16 located at the rear of dash pot 10 as viewed in FIG. 1. Shaft 15 supports dash pot arm 16 and is suitably secured thereto. Dash pot crank arm 66 is secured to shaft 15 by pin 66a or other suitable means. Crank arm 66 is forked at its lower end and secured to connecting rod 52 by pin 18. The other end of connecting rod 52 is secured to piston 45 by pin 53. Retaining pin 53a secures pin 53 to connecting rod 52 so that it cannot drift into hole 46 through piston 45. Metering pin 40 has a graduated flat 41 that forms a very small liquid passage past rod 40 and hole 46 through piston 45 when piston 45 is at the far right, as viewed in FIGS. 1 and 2. This is when the butterfly throttle valve 7 is in throttle closed position. As the piston moves to the left from its far right position this offers less resistance to throttle opening so that on a tramp down of the throttle pedal (not shown) the soft link spring 27 will compress while dash pot piston 45 allows a slow start to throttle opening and then faster motion after the throttle is partially open. The total delay from closed to full open may be early in the neighborhood of two seconds to reduce hot rodding and allow more time for the fuel from the accelerator pump (not shown but standard in many carburetors) to deliver its fuel over more revolutions of the engine than would be the case if no retarding dash pot were used.

It may be desirable to have less resistance to closing of the throttle than to opening but still have a slower rate of closing near the closed position of the throttle than near the open position. To accomplish this I have provided a passage 47 through piston 45, a metering plug 48 with a metered hole 49 and a flapper valve 50 secured to a piston 45 by pins 51. As piston 45 moves to the right in a throttle closing action, as viewed in FIGS. 1 and 2, flapper valve 50 moves to its closed position as it is supported on pins 51 so as to have limited freedom of motion or may be so thin as to be easily deflected to open and close depending on whether the higher liquid pressure is on the right or left side of pis ton 45 and flapper valve 519. The size of metering hole 49 may be changed by changing metering plug 48 in a manner similar to the changing of main fuel jets in many standard carburetors.

Dash pot 10 has liquid 70 to a level well above piston 45 and should be a liquid that will not evaporate at under hood temperatures and not vary in viscosity over under hood temperatures too much. Prestone 'has been found to be a satisfactory fluid. Some silicones may also be satisfactory.

A cover 11 is secured by screws 12. A filler plug 14 or 13 may be used to fill or inspect. Plug 13 has a feeler end 13d to determine the depth of the liquid.

Cylinder head 30 is secured by screw threads to the cylinder of dash pot 10. O-ring or compressible seal 31 seals head 30 to the cylinder and allows head to be tightened until it binds meter rod 40, then backed off a fraction of a turn to where rod 41) is not bound. Nut 30a formed integral with head 30 allows turning control of head 30 by wrench means.

In FIG. 4, I have shown the location of the foot throttle 85 pivoted to the floorboards 83 at pivot 86. Curved rod 84 bears against the foot throttle 85 at one end and the other is attached to shaft 87. Shaft 87 is supported on a bearing mounted on floorboards 83. Arm 89 is secured to shaft. By this construction the foot throttle 85 operates the soft link on shaft 22, the dash pot and the carburetor arm 6 and carburetor throttle butterfly valve 7 in the manner already described.

I have illustrated my inventions in these various forms; however, many other variations may be possible within the scope of this invention.

To those skilled in the art to which this invention relates many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and description herein are purely illustrative and are not intended to be in any sense limiting.

I claim as my invention:

1. A carburetor having a throttle valve, throttle control means for controlling said throttle valve, a soft link in said control means and a dash pot connected to said throttle valve, said dash pot having means for gradually reducing the dash pot resistance to rate of opening as the throttle valve moves from near closed throttle position to one-half wide open throttle position and second means in said dash pot for markedly reducing the dash pot resistance to a rapid rate of closing of said throttle means from wide open to fully closed as compared with the resistance to initial rate of opening of the carburetor throttle, said dash pot including a piston, a cylinder wall on which said piston rides.

2. A structure as defined in claim 1, in which said second means includes a check valve in said piston, said soft link absorbing most of the throttle opening motion of a portion of said throttle control means when that portion of said throttle control means is rapidly opened and closed as by rapid pumping, said throttle opening travel being limited during said rapid pumping being due to the resistance to rapid opening rate by said dash pot near the throttle closed position.

3. A structure as set forth in claim 2, in which there is a foot throttle connected to said throttle control means, said soft link allowing complete rapid repeated foot throttle opening and closing motions with less than one quarter carburetor throttle opening motion, said dash pot allowing full carburetor throttle opening motion with about a two second delay when said foot throttle is fully opened suddenly and held fully open.

4. A carburetor having a throttle valve, throttle control means for controlling said throttle valve, a soft link in said control means and a dash pot connected to said throttle valve, said dash pot having means for gradually reducing the dash pot resistance to rate of opening as the throttle valve moves from near closed throttle position to one-half wide open throttle position and second means in said dash pot for markedly reducing the dash pot resistance to a rapid rate of closing of said throttle means from wide open to fully closed as compared with the resistance to initial rate of opening of the carburetor throttle, said dash pot including an enclosure,

a movable wall in said enclosure, and liquid in said enclosure adjacent each side of said movable Wall.

5. A structure as defined in claim 2 in which said first 5 mentioned means includes a metering rod with a graduated fluid passage formed therein, said movable wall in said dash pot having a passage through. said movable wall, a part of said metering rod passing through said passage, the motion of said movable wall past parts of said metering pin providing diflerent size passageways for said fiuid to fiow from one side of said movable wall to the other side of said wall and thereby offer different resistances to a given moving force on said wall to move said wall and result in varying rate of movement of said wall during diiferent points in the travel of said wall, said passage being graduate-d throughout its effective length in the full travel of said movable Wall from the throttle closed position to the throttle open position of said wall, the. smaller sized openings being near the throttle closed position and the larger sized openings being near the fully opened throttle position of said dash pot movable wall, said second means including a check valve in a liquid passage from one side of said movable wall to the other side of said wall said check valve being open during throttle closing positions of said movable wall and closed during the throttle opening positions of said movable wall so that the rate of throttle opening on sudden opening motion of a portion of said throttle control means is much slower than the rate of closing of said throttle when the same portion of said throttle control mechanism is released to the throttle closed position.

6. In a carburetor having an actuator including time delay means and a throttle valve, means associated with said actuator controlling the movement of said throttle valve from closed position toward an open position at a predetermined speed at the beginning of valve movement and for increasing the speed of opening thereafter, said time delay means delaying the start of opening of the valve upon actuation of the actuator.

7. A device as in claim 6 further including means for closing the throttle valve at a predetermined rate of speed to a position adjacent the closed position and for moving the valve at a speed less than the predetermined 45 speed from said adjacent position to the closed position.

8. A device as in claim 7 further including means for closing the valve at a speed greater than theopening speed.

References Cited by the Examiner Examiners. 

6. IN A CARBURETOR HAVING AN ACTUATOR INCLUDING TIME DELAY MEANS AND A THROTTLE VALE, MEANS ASSOCIATED WITH SAID ACTUATOR CONTROLLING THE MOVEMENT OF SAID THROTTLE VALVE FROM CLOSED POSITION TOWARD AN OPEN POSITION AT A PREDETERMINED SPEED AT THE BEGINNING OF VALVE MOVEMENT 